The present invention relates generally to renewable energy and more particularly to controlling power flow in an energy converter used with a renewable energy-based power unit.
Wind turbines are one type of renewable energy-based power unit that competes with traditional forms of electric power generation. As a result, wind turbines depend on cost effective, reliable as well as safe means to capture wind energy and convert it to electrical energy that is suitable for delivery miles away. In operation, the wind turbines have a multiple of rotating blades connected to a rotor shaft that are turned by the wind. The rotation of the blades by the wind spins the rotor shaft to generate a rotational torque or force that drives one or more generators to convert mechanical energy to electrical energy. The rotor shaft and generator are mounted within a housing or nacelle that is positioned on top of a truss or tubular tower. The electrical energy generated in the nacelle is distributed down through the tower to a utility grid via a transformer.
Generally, a medium voltage is used to collect electric power from wind turbines in a typical wind power generation application. Normally, individual wind turbines disconnect from groups of turbines and a transformer in response to the blowing of a fuse in the transformer. Often times, there is a possibility that a failure in a wind turbine can arise that causes a progression of subsequent failures that are not sufficient enough to blow a fuse. Consequently, these failures can lead to the overheating and burning of electrical equipment in the wind turbine. For example, there may be a failure of electrical equipment in the wind turbine that leads to the drawing of a substantial amount of current, but not enough to reduce the voltage associated with the failure. This results in the generation of very high power which can rapidly raise the temperature of the equipment to unacceptable levels.